As part of their "Safer Space" policy, they recently starting refusing service to cops.
Note that Portland cops have already killed three people this year; one of these shootings, that of Aaron Campbell, was even criticized by the city's mayor, who said "...Aaron Campbell did not need to die that January night. The events and on-the-scene communication breakdown that occurred cost the Campbell family a son, a brother, a cousin. The Campbell family's pain, anger and outrage are real, they are justified and they deserve serious attention." Another fatal shooting was of a mentally ill man "armed" with an X-acto knife. And there have been several other questionable shootings over the past few years.
So concern that people displaying the "gang colors" of this organization may be a danger to others, are certainly justified.
Given the sort of people who make it on to the Baltimore City PD, if I owned a place in Baltimore I'd have to consider a similar policy.